Date Calculator
A date calculator computes the difference between two dates, adds or subtracts days from a starting date, and counts business days excluding weekends. Project managers use it to set deadlines, HR teams to calculate tenure and accruals, and travelers to plan multi-leg trips. The tool handles month lengths, leap years, and time-zone edge cases that trip up manual arithmetic. It turns fiddly date math into a single click so you can focus on the schedule itself. The calculator parses your input dates into Unix-style timestamps so arithmetic happens at the day level without time-of-day ambiguity. Difference mode subtracts the two timestamps and breaks the result into days, weeks, months, and years. Add and subtract mode advances the timestamp by a chosen number of days, weeks, or months while respecting calendar rollovers like month-end and leap years. Business-day mode iterates through each day in the range, skipping Saturdays and Sundays and optionally skipping holidays you specify. Common use cases: Calculating project deadlines and task durations. Computing employee tenure and leave accruals. Counting business days between two events for SLA tracking. Planning multi-leg travel itineraries across time zones. Calculating age or anniversaries from birth dates. Tips for best results: Use business-day mode for work-related calculations since calendar days often mislead stakeholders. Watch for time-zone shifts when comparing dates from different regions, since a single timestamp can land on different calendar days. Confirm whether leap years fall inside your range because they add an extra day in February. Cross-check critical results like contract end dates with a second method to catch off-by-one errors. Frequently asked questions about the date calculator: What can I calculate with this tool? You can calculate days between dates, add/subtract days from a date, calculate age, and find future or past dates. Is this tool free? Yes. It works entirely in your browser with no server calls. The Date Calculator is part of the utilities category and runs on any device with a modern browser — desktop, tablet, or phone. Everything is processed locally in the tab, so results are instant and the input is never uploaded, which also makes it safe for work and school use. Related tools: BMI & Health Calculator, Image Color Extractor, Color Contrast Checker. Read the step-by-step Date Calculator guide or browse more utilities.